Die cushion for presses



July 25, 133% Q. gm-ma 1,868,537

DIE CUSHION-FOB. PRESSES Filed Nav. 2, 1929 2 Sheets-Shasta l mi y m i@ 7 July 25,# 1932- o. KUHNER 1,868,637

DIE CUSHION FOR PRESSES Filer; Nov. 2, 1929 2 sheets-sheet 2 Patented July 26, 1932 -v *UNITED* .STA-Tes n ofrro K HNER, or GoPPIuGEN, GERMANY, AssIGNoR To k:bnn FIRMQL. soHuLER A. e., i

y 'DIE ousnroivron rnnssns Appiidation med YN wiember2,'1929,'. 'serial Nafeoalesfangi in Germain?r pin i929.

My invention relates to die cushion'sland more particularly to die cushions for die presses. 'i j Y 'It is an object of my invention to improve a die cushion of the type referredto. kTo this end 'I provid-ea cylinder with 'a piston and means connected'to a movablemember of `the press for `effecting relative movement of the piston and the cylinder; so lthat air is 'io compressedin the cylinder, andlprovide a suction valve and a'-pressureeontrolled relief valve Which valvesaopen into the same chamber of the cylinder.

The operative connection tothe movable l member of the press may be so'l designed that 'the piston is fixed and the cylinder is displaced by its connection to the movable member, or conversely the cylinderis Xed 'and the piston is displaced. Y l f` 1' Die oushionsof the kr'general type described have already been suggestedqbut in such cushions the relief valve is positively controlled by the Apiston and open vvhentheA pistonY is near the end of the stroke compressing the air which has been admitted-'through the suction valve. This, howevenis not' in accordance With the prlnciple of exertinga 'steady resistance against the kmotion of the piston as, when therelief valve is abruptly Se opened by the vpositive control the pressure is relieved as abruptly and a jerky movement of the piston Will result; A pressure-controlled relief valve, on the otlier'handyallows the pressure to build up to aipredetermined amount and then opens' gradually andlnot abruptly so that any jerkingis eliminated.

While a dieV cushion according to my invention compares favorably With the type of die cushion referred to;V it also compares favorably with die cushionsin which aprincipal and a subsidiary pressure'` medium `are employed, rand the subsidiary medium r is stor-ed in a separate tank.l :Twotanksbr sources of compressed airgatfdiil'erent'presi5 sures are therefore required in this old sys- `tem, or it is necessary to arrange several piss.

tons of various diameters in succession, and a controlvalve 1s another inevitable complication.

All thesecomplications the cylinder,

are eliminated my yinvention yin Which 'atmospheric air is drawninto lthe. cylinder of the-cushion dur inglthedownvvard stroke, compressed during the upwardstroke, andl discharged through a n relief'valve. f Preferably'the load von the re` lief valveis made variable in order toadapt insgembodying my invention are illustrated diagrammatically by I way of example, all

figure'sfbeing axial sections.v InY the drawings f Figs. }wl to y 4 illustrate cushions Withadischargevalve on thec-asing,` l j Figs. 5 to 8'y illustrate cushions with the fthe pressure at' Which it opens to various op' 'eratingconditions-fl In'the "drawings affixed to thisspecilication y V-and-forming part thereof various die cush- :discharge valve in the piston. More particv inderggf w Figsu and 4' illustrate die cushions of the types illustrated in Figs. k1 and 25 respectively, but duplicated pistons andjcylinders,

Figs. 5 and 6 illustrate die cushions' with a movable cylinder and a movable piston," respectively, las in Figs. l and '2, but withl the discharge valvefon the `piston and not on Figs. 7Yand'8` illustrate the die/,cushions according to Figs.. 5 yand 6 ini combination `Withyan auxiliarypiston in an auxiliary cyltfinder.'v f

The press towhich thedi'e cushion accordingto my invention is applied, has not been lillustrated in full detail but with what has been yshown any expert will be able` to understand the combination ofthe diecushion i i .with the press. have illustrated the diey i n cushion in combinationwith a cuppin'gor die` v il press but` it isfunderstood that it ymay be applied topresses of any type Without .depart-ly 'ing from myinvention.

Y In all hguresnis the ktable ofthe vt 'is la casing'on the' table, and pis a plate- Which is'iitted to slide in the'casing 1f.A

C5 ticularly suitable when the available space Referring now to Figs. l, 2, 5, and 6, o is a support for the blanking dies g, p, u is the male cupping die which is secured in the support 0, .7c is the ram of the press, m, is the female cupping die and 7, 7 are rods connecting the inner blanlring die g with the plate 29. Referring now to Fig. l, b is a piston which is secured to the casing t by means of a piston rod a, c is a cylinder which is fitted to slide on the piston and on the rod a, s are rods connecting the movable cylinder c with the plate p, e is a suction valve, f is a relief valve on the cylinder, and d is a pipe connecting the cylinder c with an air chamber, not shown.

CII

The suction valve e and the relief valve f are arranged in the bottom of the cylinder c. .The relief valve f is loaded by a spring z', and preferably provided with means for varying the load, for the purpose specified.

g3 lVhen the cylinder c descends under the pressure exerted on the blank support, the air above the piston l) is compressed and partly discharged into the air chamber or the like through the pipe d, while atmospheric air is drawn into the chamber below the piston b through the valve c. When the stroke of the press has been completed, the cylinder c rises under the action of the compressed air above the piston, and in turn raises the inner blanlring die g. The air below the piston is now compressed and discharged through the valve at a pressure which is a .function of the load on the spring z', so that the resistance to the upward movement of the cylinder c may be varied as required by varying the load.

Referring now to Fig. 2, the rod a of the piston Z) is connected with the plate p', the cylinder c is fixed to the casing t in the table n by stays c, and the piston l) reciprocates in .the cylinder c. Here, the compression cham- .,ber with its connection d is arranged below the piston l) and the suction chamber, with the valves e and f, is arranged above the piston.

Referring now to Fig. 3, the movable cylinder c is divided into the compartments D and D by a partition Z, the piston b is arranged in the upper compartment D as described but its rod a is exten ded through the partition Z and into the lower compartment D where a second pist-on is secured on the rodextension. Eachcompartmentisequipped 5 with the valves e and f in the suction chambers S, S" below its piston, the 'compression chamber D of the upper compartment being provided with the connection al as described, and the compression chamber e D of the lower compartment being provided with a connection d. for the same purpose. In this manner, and with the saine piston diameter', the pressure on theV blanlring die g is duplicated. This arrangement is paris restricted laterally as its width is not increased by the duplication.

The die cushion illustrated in Fig. 4; is similar to the die cushion described with reference to Fig. 3 except for the fact that its pistons b and Z2 are movable, being connected with the plate p by the rod a, and its extension. In this instance, the position of the suction and compression chambers is obviously reversed 4as compared with Fig. 3 and, in addition, the connecting pipe d in the upper compression chamber has been dispensed with, and replaced by a bore w in the piston rod extension, in combination with the pipe d in the lower compression chamber D.

Referring now to Fig. 5, this shows an arrangement similar to that described with reference to Fig. l, with a movable cylinder c and a stationary piston Z), but in this ease the relief valve Q/ is arranged in the piston Z) and not on the cylinder as in the other figures, opening toward the compression chamber D above the piston, and only the suction valve e is provided in the suction chamber below the piston. li are connecting rods extending between eyes k on the ram c, and eyes g on the casing c. The rods are free to slide in their respective eyes v and g but might be rigidly connected with one pairy of eyes. It will be understood that in this case means are required for returning the blanlring die g to its initial position as the cylinder c will cease moving in upward direction as soon as equal pressure` obtains in the chambers above and below the piston. When this occurs, the rods 7a return the cylinder c and the blanlring die g into their initial positions. Upon the downward movement of the ram, the rods /L will not influence the cylinder c.

Refering to Fig. 6, the piston is connected with the plate p asin Fig. Qiand the chamber below the piston is the compression chamber. In this instance a crosshead fr is secured on the rod a and fitted to slide on the stays o for returningthe piston Z) to its initial position in the same manner as the Cylinder c is returned by the rods L- in Fig. 5.

Referring now to Fig. 7, the arrangement is similar to that described in Fig. l but a suction chamber is only provided between the upper piston Z) and the partition Z while the cylinder 0, is open at the end below the piston b. Atmospheric pressure therefore acts on the lower face of the piston b. lVhen the cylinder c moves upwards and when the pressures have balanced between chamber D and the suction chamber S, the pressure in the second compression chamber D moves the cylinder c beyond the dead point; it will be yunderstood that the lower portion of the cylinder c constitutes an auxiliary cylinder and the rods 7L, Figs. 5 land 6, are dispensed with.

A similar operation occurs in the case of Figz 7 where the respective, position of the lla.

chambers D and D has been reversed, as yin Fig. 4, and the upper piston b is connected with the atmosphere on its upper surface. A 'i no selection of any particular modification of Y the invention is intended to the exclusion of other modifications thereof and the right to subsequently make claim to any modification not covered by these claims is expressly reserved. I claim Y' l. A. die cushion for die presses comprising a cylinder, a piston in said cylinder, means x `connected to a movable member of the press for effecting relative movement of said piston and said cylinder so as to compress air in said cylinder, a suction valve and a pressurecontrolled relief valve connected to one of the closed chambers into which the cylinder is subdivided by its piston, and a pipe connecting the other chamber to an air chamber.

2. A die cushion for die presses comprising a cylinder, a piston invsaid cylinder, means connected to a movable member of the press for effecting relative movement of said piston and said cylinder so as to compress air in said cylinder, a suction valve connected to one of the closed chambers into which the cylinder is subdivided by its piston, a pipe connecting the other chamber to an air chamber, and a pressure-controlled relief valve on said piston Which is adapted to open` into the chamber having the pipe. y c

3. A die cushion for die presses comprising a principal cylinder, a piston in said principal cylinder, means connected to amovable member of the press for effecting relative movement of said piston and said principal kcylinder so as to compress air in said principal cylinder, a suction valve connected to one of the closed chambers into which the principal cylinder is subdivided by its piston, a pipe connecting the other chamber to an air chamber, a pressure-controlled relief valve on said piston Which is adapted to open into the chamber havingthe pipe, an'auxiliary cylinder arranged on said principal cylinder at the end Where said suction valve is' arranged, and the outer end of said auxiliary cylinder being open to. atmosphere, and a. piston in said auxiliary cylinder operatively coinected to the piston in said principal cyl- 1n er. Y

OTTO KI-INER.

person skilled l' 

